D'Alessio joined Jimmy Patsos' staff at Siena on May 1, 2013.
D'Alessio worked under Patsos for three years at Loyola, where he assisted with all aspects of the program, including: recruiting, scouting and player development. D'Alessio helped the Loyola program achieve great success in his three seasons, highlighted by a 47-21 record the last two years and a NCAA Second Round Tournament appearance in 2012.
D'Alessio enjoyed great success at Division II Bowie State before arriving in Baltimore. He compiled a 199-96 record over 10 seasons as head coach, and orchestrated three consecutive trips to the National Tournament (2002-2005) and a trip to the 2003 NCAA Division II Final Four. In his second season, he led the Bulldogs to their first winning record (19-9) in 30 years, and the NCAA appearances were the first in the history of the school.
After leaving Bowie, D'Alessio worked as head coach for the UCC Blue Demons, a professional team in Cork, Ireland. He led the Blue Demons to a 16-8 final record (.667) in 2009-10, and a berth in the national league championship playoffs.
D'Alessio was the head coach at CCBC-Catonsville from 1993-1999, turning around a program that posted 14 consecutive losing seasons prior to his arrival. By his third season in 1995-96, the Cardinals were 28-7, beginning a string of four straight 20-win seasons. The 95-96 season ended with a trip to the JUCO Elite Eight following a Region XX Championship. D'Alessio's record during his tenure at CCBC-Catonsville was 124-52 (.700).
D'Alessio led both Bowie State (2005) and CCBC-Catonsville (1999) to No. 1 national rankings during his tenure.
D'Alessio is one of many coaches who learned under Jack Bruen at The Catholic University of America. D'Alessio was a two-time all-conference player for the Cardinals while scoring 936 points. After a short stint as the junior varsity coach at Good Counsel HS following his playing days, he returned to his alma mater to spend six seasons as an assistant, serving under both Bruen (1986-1989) and Bob Valvano (1989-1992). His players at Catholic included current Siena coach Jimmy Patsos.
D'Alessio graduated from Catholic with a bachelor's degree in accounting in 1983. He has three children: Jacob, Elena, and Alex.